1. METABOLISM

2. Cell Metabolism Sum of all chemical reactions Catabolic pathways:
break down
release energy
cellular respiration
Anabolic pathways:
build
consume energy
photosynthesis

3. ENERGY Capacity to do work Kinetic: energy of motion Potential: stored
Chemical: potential, stored in molecules
Thermodynamics
Energy cannot be created or destroyed
Energy transformation ↑ entropy of universe

4. Free energy – portion that can perform work when temp
Free energy – portion that can perform work when temp. uniform; available for work

5. Exergonic and Endergonic Reactions

6. Closed & Open Systems
Glucose is broken down in a series of exergonic reactions that power the work of the cell.
The product of each reaction becomes the reactant for the next

7. ATP – adenosine triphosphate

8. Energy coupling by phosphate transfer.
ATP hydrolysis provides the energy to convert glutamic acid to glutamine

9. ATP CYCLE ATP + H20↔ ADP + Pi + energy

10. ENZYMES Organic catalysts Lower activation energy Substrate specific
Active site
Affected by environmental factors
Not consumed in the reaction

11. Hydrolysis of Sucrose

12. REACTANTS
AB: sucrose
(glucose & fructose)
CD: water
(hydroxyl & hydrogen)
PRODUCTS
AC: glucose
BD: fructose

13. Enzymes lower activation energy

16. Inhibition of Enzyme Activity
No inhibition – substrate can bind to active site
Competitive inhibition – inhibitor mimics the substrate and competes for the active site.
Noncompetitive inhibition – inhibitor binds to enzyme at site other than active site and alters the shape of the active site (no longer functional)

17. Allosteric Interactions
Two or more polypeptides subunits, both with active sites.
Allosteric sites – specific receptors for enzyme regulators, may be activators or inhibitors.
Changes in response to concentration of regulators
AMP (activator) & ATP (inhibitor) may fit same allosteric site

18. Feedback Inhibition Ex. Inhibition of ATP generating pathway
Switching off of a pathway by its end product
Promotes cell efficiency – cell does not waste resources making more product than necessary

19. Cooperativity - amplifies the response to substrates -one substrate primes an enzyme to readily accept additional molecules

20. Localization: Cell structures bring order
Multienzyme complex: assembles team of enzymes for entire metabolic pathway
Fixed location within cell on membranes
In solution within organelles